High-temperature oxidation of a Ti-15V-3Cr-3Sn-3Al alloy in CO2 atmosphere

The oxidation of a Ti-15V-3Cr-3Sn-3Al alloy has been investigated in the te mperature range of 1000K to 1400K in CO2 atmosphere. The results of optical microscopy, electron probe microanalyses and powder X-ray diffraction meas urements on the oxide scales formed during oxidation indicate that the scal es consist of an external and an internal scale. The oxide phases and the c arbide phase formed at 1100 similar to 1300K are identified as tetragonal-T iO2, orthorhombic-TiO2, alpha -Al2O3, V2O5 and TiC. The oxides formed at 14 00K are identified as SnO2 together with the oxides and the carbide describ ed above. The parabolic rate laws were confirmed on the growth of the inter nal scale layer and the permeation depth of oxygen in the alloy with the ap parent activation energies, 210 kJ/mol and 166 kJ/mol, respectively.